The Belfast and County Down Railway was set up on 26 June 1846, the first section ran from Belfast to Hollywood was opened on 2 August 1848. In 1865 the line was extended to Bangor by the (BHBR) Belfast, Hollywood and Bangor Railway. 1869 saw a line completed to Newcastle by the Downpatrick, Dundrum and Newcastle Railway.

The mid 1800's was the heyday of the Irish railways, in 1858 a branch to Ballynahinch was opened, one from Downpatrick to Ardglass was opened in 1892, Castlewellan was connected to the network in 1906.

Prior to 1948 the transport system in Northern Ireland was in the hands of many independent companies, in that year the Stormont Government introduced the Transport Act (NI) which empowered them to nationalize the railways, on 1st October 1948 Ulster Transport Authority (UTA) was set up. They took over 29 locomotives, 181 carriages, 629 wagons designed for goods and livestock, as well as 54 service vehicles and 6 vans built to carry fish.

Many thought that the new company would give Ulster's railways a new lease of life, they were to be disappointed, a mere two years later in 1950 all the lines with the exception of the Belfast to Bangor section were closed.

During the the railways history it had one major disaster which occurred at Ballymacarrett in 1845 in which 23 passengers lost their lives.

See the history of Irish Railways. Today the spectacle of a steam train once almost as common as the juggernauts which make possible our modern way of life, have largely passed into history. Except that is for several railway preservation societies which do a sterling job keeping the heritage alive, one such is the The Downpatrick and Co. Down Railway which run steam trains during the summer and holiday periods, visit their site for more information.

See also The Chronology of Irish Railways.